Search

In May 2024 the strongest geomagnetic storm since the Halloween storms of 2003 occurred. Media reported worldwide about the space weather situation and its effects on the infrastructure. Of particular interest were reports claiming severe effects on the radiation exposure at aviation altitudes, although no data supporting this assertion were available at that time. In this work the different aspects that affect the radiation exposure at aviation altitudes are discussed for the event. Furthermore, the corresponding dose rates are evaluated and compared to data from Low Earth Orbit. Model calculations indicate an additional contribution to the radiation field at aviation altitudes due to this extraordinary space weather situation, although the dose rates were still in the lowest category D0 of the space weather D-index, i.e., within the dose rate variation of a solar cycle. [ABSTRACT FROM AUTHOR]

The effect of a tilted-dipole three-dimensional corotating interaction region (CIR) on the transport and acceleration of solar energetic particles (SEPs) is studied. In this work, we discussed how the particle intensity longitudinal and radial dependence might be influenced by the background structures. Moreover, we investigate how the spectral index distribution is modulated by the CIR structure. We use the focused transport equation (FTE) to describe the propagation and acceleration of SEPs in a tilt-dipole 3D CIR, generated by the high-resolution 3D magnetohydrodynamic (MHD) model. The forward stochastic differential method is used to solve the FTE. The protons with the \begin{document}$ E^{-4.4} $\end{document} spectrum from 0.5 to 15 MeV are injected uniformly at the heliographic equator of 0.15 AU. Physical quantities are extracted along each interplanetary magnetic field (IMF) line to show the results. In the tilted-dipole CIR background, if injected from the solar equator at the inner boundary, particles in the slow flow are transported to higher latitudes due to the extension of the IMF lines to higher latitudes. The longitudinal patterns of the particles are dominated by the density of IMF lines. The focusing effect modulates the longitudinal variation of the particle intensity and gives rise to new longitudinal intensity peaks. The adiabatic effect largely increases the intensity fluctuation along the longitude. The structure of the solar wind can also lead to the difference of the index \begin{document}$ \alpha $\end{document} in the empirical function \begin{document}$ I_{{\mathrm{max}}}=kR^{-\alpha} $\end{document}, describing the radial variation of peak intensity according to our simulation. Under the influence of the CIR structure, the index \begin{document}$ \alpha $\end{document} varies from 1.9 to 3.4 at 0.3−1.0 AU. The variation of the solar wind speed should be considered when estimating the radial dependence of the SEP peak intensity. The spectra indices rise near the CIR boundaries and drop near the stream interface (SI). The adiabatic effect makes the spatial variability of the spectral index larger. The spectral index could be similar at different radial distances in the CIR structure.

The Solar MAgnetic Connection HAUS1 tool (Solar-MACH) is an open-source tool completely written in Python that derives and visualizes the spatial configuration and solar magnetic connection of different observers (i.e., spacecraft or planets) in the heliosphere at different times. For doing this, the magnetic connection in the interplanetary space is obtained by the classic Parker Heliospheric Magnetic Field (HMF). In close vicinity of the Sun, a Potential Field Source Surface (PFSS) model can be applied to connect the HMF to the solar photosphere. Solar-MACH is especially aimed at providing publication-ready figures for the analyses of Solar Energetic Particle events (SEPs) or solar transients such as Coronal Mass Ejections (CMEs). It is provided as an installable Python package (listed on PyPI and conda-forge), but also as a web tool at solar-mach.github.io that completely runs in any web browser and requires neither Python knowledge nor installation. The development of Solar-MACH is open to everyone and takes place on GitHub, where the source code is publicly available under the BSD 3-Clause License. Established Python libraries like sunpy and pfsspy are utilized to obtain functionalities when possible. In this article, the Python code of Solar-MACH is explained, and its functionality is demonstrated using real science examples. In addition, we introduce the overarching SERPENTINE project, the umbrella under which the recent development took place.

Solar Energetic Particles (SEPs) are charged particles accelerated within the solar atmosphere or the interplanetary space by explosive phenomena such as solar flares or Coronal Mass Ejections (CMEs). Once injected into the interplanetary space, they can propagate towards Earth, causing space weather related phenomena. For their analysis, interplanetary in situ measurements of charged particles are key. The recently expanded spacecraft fleet in the heliosphere not only provides much-needed additional vantage points, but also increases the variety of missions and instruments for which data loading and processing tools are needed. This manuscript introduces a series of Python functions that will enable the scientific community to download, load, and visualize charged particle measurements of the current space missions that are especially relevant to particle research as time series or dynamic spectra. In addition, further analytical functionality is provided that allows the determination of SEP onset times as well as their inferred injection times. The full workflow, which is intended to be run within Jupyter Notebooks and can also be approachable for Python laymen, will be presented with scientific examples. All functions are written in Python, with the source code publicly available at GitHub under a permissive license. Where appropriate, available Python libraries are used, and their application is described.

Cosmic rays (CRs) are considered the primary energetic particle source of atmospheric ionization on Earth. Under the modulation of severe solar eruption events, CR variations are further speculated to impact the Earth's lightning activities. Previous researches show that CR intensity and lightning incidence are positively correlated on the time scale of several days to decades. However, to our knowledge, the global lightning response to short-term CR variation has not been studied in the literature. Ground level enhancements (GLEs) provide the opportunity to study such a possible link. As a small fraction of solar energetic particle events that could reach the energy level of several GeVs, GLEs can thus generate atmospheric cascades that could be recorded by ground-based neutron monitors. Furthermore, as GLEs generally take place within several 10 min to an hour, the lightning variations caused by potential meteorological factors could be maximally diminished in such a short time. During the operational period of the World Wide Lightning Location Network (Aug 2004 to now), three typical GLEs with the intensity >15% are analyzed from the International GLE Database, namely #69 (Jan 20, 2005), #70 (Dec 13, 2006), and #71 (May 17, 2012). For each GLE event, the global lightning incidence presents a positive response to GLE (i.e., a significant enhancement within 20 min right after the GLE onset). Meanwhile, the relative amplitude of lightning response seems to be in direct proportion to GLE intensity (i.e., the more intensive the GLE is, the more obvious the increase in the lightning incidence is), which is further verified to be statistically significant by Monte Carlo test. By comparing lightning responses in different latitudinal zones, we find that more intensive lightning responses to GLEs seem to be at higher latitudes.

Abstract: On 10 September 2017, solar energetic particles originating from the active region 12673 produced a ground level enhancement at Earth. The ground level enhancement on the surface of Mars, 160 longitudinally east of Earth, observed by the Radiation Assessment Detector (RAD) was the largest since the landing of the Curiosity rover in August 2012. Based on multipoint coronagraph images and the Graduated Cylindrical Shell model, we identify the initial 3‐D kinematics of an extremely fast coronal mass ejection (CME) and its shock front, as well as another two CMEs launched hours earlier with moderate speeds. The three CMEs interacted as they propagated outward into the heliosphere and merged into a complex interplanetary CME (ICME). The arrival of the shock and ICME at Mars caused a very significant Forbush decrease seen by RAD only a few hours later than that at Earth, which was about 0.5 AU closer to the Sun. We investigate the propagation of the three CMEs and the merged ICME together with the shock, using the drag‐based model and the WSA‐ENLIL plus cone model constrained by the in situ observations. The synergistic study of the ICME and solar energetic particle arrivals at Earth and Mars suggests that to better predict potentially hazardous space weather impacts at Earth and other heliospheric locations for human exploration missions, it is essential to analyze (1) the eruption of the flare and CME at the Sun, (2) the CME kinematics, especially during their interactions, and (3) the spatially and temporally varying heliospheric conditions, such as the evolution and propagation of the stream interaction regions. [ABSTRACT FROM AUTHOR]

Abstract: Mewaldt et al. (2012) fitted the observations of the ground level enhancement (GLE) events during solar cycle 23 to the double power law equation to obtain the four spectral parameters, the normalization constant C, low‐energy power law slope γ1, high‐energy power law slope γ2, and break energy E0. There are 16 GLEs from which we select 13 for study by excluding some events with complicated situation. We analyze the four parameters with conditions of the corresponding solar events. According to solar event conditions, we divide the GLEs into two groups, one with strong acceleration by interplanetary shocks and another one without strong acceleration. By fitting the four parameters with solar event conditions we obtain models of the parameters for the two groups of GLEs separately. Therefore, we establish a model of energy spectrum of solar cycle 23 GLEs, which may be used in prediction in the future. [ABSTRACT FROM AUTHOR]

The multifunctional spectrometer (MFS) is a new radiation monitor that together with component technology test bed makes the European Space Agency Alphasat Environment and Effects Facility—Technology Demonstration Payload 8 (AEEF-TDP8). The two units are hosted in the X panel of the Alphasat satellite in orbit since July 2013. MFS is an instrument specifically designed to characterize the space radiation environment in geostationary orbit. The mission lifetime of AEEF/TDP8 will be at least three years and TDP8 is expected to be acquiring scientific data during the whole period. Before launch, MFS was submitted to proton and electron beam tests at the Paul Scherrer Institute in Switzerland in 2010. The main purpose was the validation and calibration of the MFS protoflight model together with the estimation of particle energy resolution and identification capability. A full Geant4 simulation with computer-aided design geometry exported to geometry description markup language description the MFS in-flight configuration was built. Ground test results were validated with Geant4 simulation. The measurements of MFS proton channels and MFS proton response functions are validated using comparisons with INTErnational Gamma-Ray Astrophysics Laboratory/INTEGRAL Radiation Environment Monitor data during the solar energetic particle event of January 2014. In addition, an artificial neural network (ANN) unfolding method was developed in order to unfold MFS data. Comparisons show that the derived ANN Alphasat/MFS fluxes are in remarkable agreement with INTEGRAL/IREM proton fluxes. [ABSTRACT FROM PUBLISHER]